found this on an old thread.
Had the same problem after SoU update. By looking at Hearthstone logs I saw that cache folder was causing problems. If you have same problems try cuting folder Cache from C:\Users\yourname\AppData\Local\Blizzard\Hearthstone and passing it on desktop. After that try to lunch battle.net and the game again, if it starts just delete that folder from desktop, if not return it where you cut it from. Hope it works 
I would maybe send a support ticket to the developers and see if they can fix it.